Iron is essential for many metabolic processes but can also cause damage. As a potent generator of hydroxyl radical, the most reactive of the free radicals, iron can cause considerable oxidative stress. Since iron is absorbed through diet but not excreted except through menstruation, total body iron levels buildup with age. Macular iron levels increase with age, in both men and women. This iron has the potential to contribute to retinal degeneration. Here we present an overview of the evidence suggesting that iron may contribute to retinal degenerations. Intraocular iron foreign bodies cause retinal degeneration. Retinal iron buildup resulting from hereditary iron homeostasis disorders aceruloplasminemia, Friedreich's ataxia, and panthothenate kinase-associated neurodegeneration cause retinal degeneration. Mice with targeted mutation of the iron exporter ceruloplasmin have age-dependent retinal iron overload and a resulting retinal degeneration with features of age-related macular degeneration (AMD). Post mortem retinas from patients with AMD have more iron and the iron carrier transferrin than age-matched controls. Over the past 10 years much has been learned about the intricate network of proteins involved in iron handling. Many of these, including transferrin, transferrin receptor, divalent metal transporter-1, ferritin, ferroportin, ceruloplasmin, hephaestin, iron-regulatory protein, and histocompatibility leukocyte antigen class I-like protein involved in iron homeostasis (HFE) have been found in the retina. Some of these proteins have been found in the cornea and lens as well. Levels of the iron carrier transferrin are high in the aqueous and vitreous humors. The functions of these proteins in other tissues, combined with studies on cultured ocular tissues, genetically engineered mice, and eye exams on patients with hereditary iron diseases provide clues regarding their ocular functions. Iron may play a role in a broad range of ocular diseases, including glaucoma, cataract, AMD, and conditions causing intraocular hemorrhage. While iron deficiency must be prevented, the therapeutic potential of limiting iron-induced ocular oxidative damage is high. Systemic, local, or topical iron chelation with an expanding repertoire of drugs has clinical potential.
Acute retinal necrosis (ARN), also known as Kirisawa-type uveitis, is an uncommon condition caused by infection of the retina by one of the herpes family of viruses, most typically varicella zoster virus or herpes simplex virus and less commonly cytomegalovirus. Clinical diagnosis can be challenging and is often aided by PCR-based analysis of ocular fluids. Treatment typically involves extended use of one or more antiviral agents. Long term retinal detachment risk is high. We review the literature on ARN and present an approach to the diagnosis and management of this serious condition.
While it has been known for years that iron overload is associated with retinal degeneration in the context of ocular siderosis, intraocular hemorrhage, and the hereditary diseases aceruloplasminemia and pantothenate kinase associated neurodegeneration, recent evidence suggests that age-related macular degeneration (AMD) may also be exacerbated by retinal iron overload. In the retina, iron is necessary for normal cellular function. Iron overload, however, can cause retinal toxicity through the generation of oxygen free radicals. Histopathology of eyes with macular degeneration has shown elevated levels of iron in the retinal pigment epithelium, Bruch membrane, and within drusen, some of which was chelatable in vitro with deferoxamine. In this review, the authors summarize the evidence that iron overload may contribute to AMD pathogenesis. It is hoped that continued investigation of the role of iron and iron associated proteins in the retina will uncover clues to AMD pathogenesis and lead to new preventative or therapeutic options.
These data demonstrate that transferrin expression is increased in the retinas of patients with AMD relative to those of healthy control patients of comparable age. Along with previous studies that have demonstrated elevated iron levels in AMD retinas, early onset drusen formation in a patient with retinal iron overload resulting from aceruloplasminemia, and retinal degeneration with some features of macular degeneration in the iron-overloaded retinas of ceruloplasmin/hephestin knockout mice, the present study suggests that altered iron homeostasis is associated with AMD.
Herein, we report the largest series of nine cases of peripheral chorioretinal degeneration secondary to didanosine toxicity in adults. When combined with the cases in the literature, 19 cases of didanosine toxicity, 4 of which occurred in children, were collected and analyzed. Three of the new cases presented showed clear progression of degeneration despite didanosine cessation. Newer nucleoside reverse transcriptase inhibitors may potentiate mitochondrial DNA damage and lead to continued chorioretinal degeneration.
Intravitreal injection of expansile sulfur hexafluoride gas is a low-cost and minimally invasive alternative for the treatment of symptomatic VMT syndrome. Further study is warranted.
Purpose: This work analyzes a series of eyes with brolucizumab-associated intraocular inflammation (IOI) without retinal vasculitis reported to the American Society of Retina Specialists. Methods: The American Society of Retina Specialists Research and Safety in Therapeutics Committee analyzed clinical characteristics from submitted reports of IOI after brolucizumab. Eyes with retinal vasculitis or that received intraocular antibiotics were excluded. Results: Forty-nine eyes of 45 patients were collected. Mean visual acuity (VA) at baseline was 20/49 (range, 20/20-5/200). Patients presented with IOI a mean of 24 days (range, 3-63 days) after their most recent brolucizumab injection; 61% presented for an unscheduled visit while 39% presented at routine follow-up. Mean VA at IOI presentation was 20/67 (range, 20/20-3/200). The most common symptoms were floaters (78%) and blurry vision (76%). Pain (20%) and redness (16%) were less common; 3 (6%) eyes were asymptomatic. IOI was anterior only in 18%, posterior only in 31%, and both anterior and posterior in 51% of eyes. Treatment included topical steroids alone in 67% of eyes, whereas 10% of eyes received no treatment. Mean VA at last follow-up was 20/56 (range, 20/20-1/200). Three (6%) eyes lost 3 or more lines and 1 (2%) eye lost 6 or more lines. Conclusions: Brolucizumab-associated IOI without retinal vasculitis typically presented with a delayed onset of a few weeks. Often, VA decline was relatively mild. Most symptoms resolved and nearly all had a return-to-baseline VA, but a small percentage of patients had a significant decrease in VA at last follow-up.
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